1. By Team Funky Beams (+ Chuck)
The Ideal Array
By Team Funky Beams
(+ Chuck)

2. Preprocessing courtesy of Chuck
Download and unpack seed file
Create and populate event directories with synchronized time windows of event sacs
Remove instrument response
Rotate ENZ to RTZ
Preprocessing courtesy of Chuck

3. Select subset of OK array of interest
For the Z and T components
For the gradiometer and the golay array
For each array and frequency
Determine array response
For P and S waves
Gradiometry analysis
Compute Beamforming

4. Array Geometries and Co-Arrays

5. What is Beamforming? Rost & Thomas, 2002 5 stations array
Signals: time arrival (geometry,slowness)
Plane wave
Signals shifted with the phase slowness
Stack
Beamforming

6. Array Response Comparison (0.5-4 Hz)
Golay
Grad H
Cross

7. Array Response Comparison (1-12 Hz)
Golay
Grad H
Cross

8. Array Response Comparison (10-20 Hz)
Golay
Grad H
Cross

9. Earthquake within Fairview cluster
:29:38 (UTC)
98 km from OK array
M 4.2

10. Beamforming - P wave Golay 0.51-25 Hz Golay 0.96-4.18 Hz

11. Beamforming - S wave Golay 0.51-25 Hz Golay 0.96-4.18 Hz

12. Beamforming ComparisonHz Hz Hz Hz Hz
P-wave
S-wave

13. Line array

14. What is Gradiometry?

15. geometrical spreading
What is Gradiometry?
geometrical spreading
horizontal slowness

16. gradient of displacement
What is Gradiometry?
gradient of displacement

17. numerically calculate numerically calculate
What is Gradiometry?
numerically calculate
numerically calculate
measure
invert

18. Gradiometry (Vertical) - Golay Array
Filtered Hz
u(t)
Azimuth
Mean =
Slowness
Mean =
Geo. Spr.
Rad. Patt.

19. Gradiometry (Transverse) - Golay Array
Filtered Hz
u(t)
Azimuth
Mean = 82.14
Slowness
Mean =
Geo. Spr.
Rad. Patt.

20. Gradiometry (Vertical) - Gradiometer
Filtered 2-3 Hz
u(t)
Mean =
Azimuth
Slowness
Mean = 0.165
Geo. Spr.
Rad. Patt.

21. Gradiometry (Transverse) - Gradiometer
Filtered 2-3 Hz
u(t)
Mean =
Azimuth
Mean =
Slowness
Geo. Spr.
Rad. Patt.

22. Thank you / merci beaucoup
Conclusions
Aperture is an important control over the resolution
Golay array is efficient for beamforming
Station spacing heavily influences aliasing
Gradiometry is more influenced by station spacing
Thank you / merci beaucoup
Chuck, IRIS, et al.!!!

23. Fin